Pilot Study on the Effects of Psilocybin on Belief Updating and Insight Formation

Conditions

• Phase I

Eligibility Criteria

Sex

ALL

Age

18 Years - N/A

Healthy Volunteers

Accepted

Interventions

• Psilocybin (Usona Institute) — DRUG
  1 dose of psilocybin 25 mg oral capsule
• Inactive Placebo (Usona Institute) — DRUG
  1 dose of Microcrystalline Cellulose (MCC) 25 mg capsule

Study Details

The primary aim of this phase I mechanistic pilot study is to evaluate the effects of psilocybin on aspects of cognition in healthy adult volunteers. Up to 24 participants will receive a single dose of either psilocybin or inert placebo, and they will be asked to complete several computer-based behavioral tasks measuring features of learning, belief updating, and abstraction. Participants will also complete measures of subjective experience and expectancy, as well as semi-structured interviews at follow up, to assess whether experience correlates with behavior. This is a Voluntary Submission.

Key Dates

First listed

Sep 14, 2026

Start date

Nov 30, 2026

Status verified

Aug 2026

Primary completion

Nov 30, 2027

Completion

Nov 30, 2027

Study Design

Enrollment

24 participants (estimated)

Allocation

RANDOMIZED

Intervention model

PARALLEL

Primary purpose

BASIC_SCIENCE

Arms

• Experimental: Psilocybin
  Psilocybin 25 mg oral capsule
• Placebo Comparator: Inert Placebo
  Microcrystalline cellulose 25 mg oral capsule

Primary Outcome Measure

Reinforcement Learning and Abstraction Task [ Time Frame: During dosing session and 1 day after the dosing session ]

Locations (1)

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